How monarchs make it to Mexico without a map. Each fall, monarch butterflies across Canada and the United States turn their colorful wings toward the Rio Grande and migrate more than 2,000 miles to the relative warmth of central Mexico.
The journey, repeated instinctively by generations of monarchs, continues even as their numbers have plummeted due to loss of their sole larval food source—milkweed. Now, scientists think they have cracked the secret of the internal, genetically encoded compass monarchs use to determine the southwest direction they should fly each fall. Like rivers on land, melting water erodes Greenland's ice. To get a clearer idea of how Greenland’s ice sheet is responding to climate change, scientists are taking a closer look at the drainage channels of water as it melts during the summer.
The work suggests the resulting erosion on the ice sheet shapes landscapes similarly to, but much faster than, rivers do on land. “How fast is the ice sheet melting, and how much the melt will contribute to rising sea levels are important questions,” says Leif Karlstrom, a professor in geological sciences at the University of Oregon. “It is important to quantify the melt rate, but that is not easy. “Our study allows us to use geometric characteristics of the channel network—their patterns on the landscape—as a diagnostic tool.”
Projections on sea-level rise, such as those done with remote sensing or satellite observations, he says, have been difficult to determine accurately because melt rates vary widely each year, based on such factors as summer temperatures and elevations across the ice sheet. Audio Player. Loss of milkweeds means monarchs could go extinct. There is a good chance that monarch butterflies will face a “quasi-extinction” in the next 20 years, researchers warn.
Despite a favorable summer in 2015, the eastern migratory population declined 84 percent between 1996 and 2014. Quasi-extinction means that so few individual monarchs would exist that their migratory patterns would collapse and the population likely wouldn’t recover. For a new study, published in the journal Scientific Reports, researchers used historic trends to develop models that forecast future monarch populations. The team factored weather patterns and natural variations into the simulations and figured out the probability of the overall population sinking to various thresholds that could lead to quasi-extinction. Saving the monarchs from extinction will require “all hands on deck.” The researchers tracked the current population of monarchs by measuring the area of land they occupied while overwintering in central Mexico.
Source: Iowa State University. Visite de Fukushima Daiichi - A. Gundersen 03.10.2013. Recevant de nombreuses questions sur la situation à la centrale nucléaire de Fukushima Daiichi, Arnie Gundersen, ingénieur en chef de Fairewinds, nous propose une visite du site en vidéo, combinant images satellite, animations 3D et photographies.
Nous aurons ainsi une vision du site depuis la construction de la première unité, Daiichi 1, jusqu'aux 2 bâtiments les plus récents des unités 5 et 6. Nous verrons que dès la conception de la première unité en 1965, qui servira de modèle à ses trois voisines construites par la suite, les décisions maîtresses prises par les ingénieurs des sociétés General Electric et EBASCO, basées en premier lieu sur des considérations financières de réduction des coûts, scelleront dans le béton le sort du site et de la nation Japonaise entière, plus de 45 ans plus tard.
La visite commencera par le parc des citernes de stockage de l'eau contaminée, qui ne cesse de s'étendre. Comme le dit Gundersen dans une autre de ses productions que j'espère aborder également, About Futurity. Futurity features the latest discoveries by scientists at top research universities in the US, UK, Canada, and Australia.
The nonprofit site, which launched in 2009, is supported solely by its university partners (listed below) in an effort to share research news directly with the public. Contacts firstname.lastname@example.org 615 Hylan Hall University of Rochester Rochester, NY 14627 Jenny Leonard, email@example.com (585) 275-6076 Katie George, assistant firstname.lastname@example.org (585) 276-4508 Liz Goodfellow, assistant email@example.com (585) 276-6186. Earth & Environment. Natural gas system in US is leaking methane. Officials in the United States have underestimated how much methane—a potent greenhouse gas—is leaking from the country’s natural gas system, experts warn.
The findings, published in the journal Science, are based on a review of more than 200 earlier studies and confirm that methane emissions are considerably higher than official estimates, including those by the Environmental Protection Agency (EPA). Natural gas consists predominantly of methane. Even small leaks from the natural gas system are important because methane is a greenhouse gas that is about 30 times more potent than carbon dioxide. “People who go out and actually measure methane pretty consistently find more emissions than we expect,” says the lead author of the new analysis, Adam Brandt, an assistant professor of energy resources engineering at Stanford University. “Atmospheric tests covering the entire country indicate emissions around 50 percent more than EPA estimates,” says Brandt. EPA’s estimates are too low.